Anastomotic devices and methods

ABSTRACT

Exemplary embodiments comprise AV fistulas and other anastomotic devices for creating new or reinforcing existing side-branch vessels, and/or bridging neighboring vessels together. An exemplary embodiment may comprise a sidewall port, such as a flanged sidewall port, and/or flow frame design, such as a partially bare, flexible stent or a whisk, for purposes of creating a transmural flow. Another exemplary embodiment may comprise a compliant vessel support to aid in the transition from device to vessel and/or vessel to device, and to promote vessel dilation.

CROSS REFERENCE RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.15/267,312, filed Sep. 16, 2016, which is a Continuation of U.S.application Ser. No. 13/229,540, filed Sep. 9, 2011, now U.S. Pat. No.9,463,269, issued Oct. 11, 2016, which claims priority to and thebenefit of Provisional Application Ser. No. 61/381,655, filed Sep. 10,2010, all of which are incorporated by reference herein in theirentireties.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to anastomotic and blood access devices andmethods, more specifically to vascular access fistulas and side-branchdevices.

Discussion of the Related Art

In the United States alone, approximately 400,000 people have end-stagerenal disease requiring chronic hemodialysis. Hemodialysis replaceskidney function by removing toxins from the blood that are normallyremoved by healthy kidneys. In order to remove toxins effectively, bloodmust be passed at a high blood flow rate through a hemodialysis machine.This high blood flow is best achieved by the creation of a permanentvascular access site that includes an arteriovenous (AV) anastomosis inwhich a vein is attached to an artery to form a high-flow shunt orfistula, commonly referred to as an AV fistula. AV fistulas are widelypreferred for use in connection with hemodialysis vascular access basedon their superior patency, low complication rates, lower cost to thehealthcare system, and decreased risk of patient mortality.

In creating an AV fistula, typically, a vein is directly attached to anartery, and then six to eight weeks from the time of attachment isusually required for the fistula to sufficiently mature, i.e. to provideadequate blood flow, to be cannulated for dialysis, etc. Fistulamaturation requires a compliant and responsive vasculature capable ofdilating in response to the increased velocity of blood flowing into thenewly created low-resistance circuit. Failure to mature of new fistulasremains a major obstacle to increasing the proportion of dialysispatients with fistulas.

In addition, waiting for a fistula to mature exposes those patients inneed of more immediate dialysis to increased risk, because aless-desirable temporary access device may be employed. Typically, thistemporary access device is a catheter, to be inserted for hemodialysisaccess until the fistula has matured. The use of a temporary catheteraccess exposes the patient to additional risk of bleeding and infection,as well as discomfort, and is associated with a 91% higher mortalityrate compared to fistulas. In trying to increase the prevalence offistulas in the U.S., a proportional rise in catheter use has beendocumented.

Moreover, some people are less than ideal candidates for a fistula. Forexample, if the vascular system is greatly compromised, a fistula maynot be attempted because the implantation may require an invasivesurgical procedure that causes trauma to vessel walls and thus, is toorisky for those with a weakened vasculature. In addition, AV fistula maynot be feasible in all patients due to anatomical considerations.

Accordingly, there is a need for AV fistulas exhibiting the ability toimprove the maturation rates of AV fistulas, reduce the instances of AVfistula failure, and minimize the extent of vessel trauma duringimplantation and thereafter.

SUMMARY OF THE INVENTION

According to one aspect of the invention, a vascular access fistuladevice has a generally continuous conduit to allow blood flow between anartery and a vein having inner walls after a deployment of the device ina body. The fistula device has an arterial segment that extends into theartery after deployment. The fistula device has a venous segment thatextends into the vein after deployment. The fistula device further has abody that extends longitudinally between the arterial segment and thevenous segment. The fistula device includes a first flange that extendsoutwardly from the arterial segment. The first flange mechanicallyengages an arterial wall upon deployment of the fistula device to securethe fistula device to the artery. The fistula device also includes acompliant support formed on the venous segment that expands outwardlytoward the inner walls of the vein. The compliant support is flexibleand generally compliant to minimize radial distension of the vein afterdeployment of the venous segment in the vein. In an exemplaryembodiment, the compliant support may be configured to reduce or blockretrograde blood flow.

According to another aspect of the invention, a sidewall port devicecomprises dual flanges and is coupled to a conduit wherein the dualflanges engage an aperture in a vascular wall. Each flange of the dualflanges extends radially outwardly with respect to the aperture in thevascular wall. The flanges mechanically engage both luminal andabluminal surfaces of the arterial wall for fixedly securing the stentgraft to the vascular wall and generally creating an end-to-sidesutureless anastomosis.

According to another aspect of the invention, a stent graft comprises asidewall port device having dual flanges for coupling the stent graft toa surgically made aperture in a vascular wall or another stent device.According to another aspect of the invention, a stent graft includes asingle flange for coupling a conduit through an aperture in a vascularwall and/or the wall of another stent device. A single flange extendsgenerally radially outwardly from an end of the stent graft and residesin proximity to the luminal wall of vessel and/or stent device upondeployment. The single flange mechanically engages the luminal wall andmay be held in place against the vessel wall by fluid pressure and/or aninterference fit. The single flange portion reduces the effect ofnecrosis of the vessel by reducing the pinch force of the vessel wall.

According to another aspect of the invention, a vascular access fistuladevice may comprise a conduit to allow blood flow between two vessels,such as an artery and a vein, and a flow frame connected thereto orintegral with a conduit configured to allow downstream perfusion inaddition to transmural flow. Stated differently, the flow frame, whichmay be comprised of any structure or material (e.g., whether metallic orpolymeric), may be configured to not obstruct flow through the nativeconduit or vessel. In this regard, the flow frame may comprise abranched conduit, an elbow conduit, a stent, a stent graft, a modifiedstent graft to have a window cutout or bare stent area, a siphon, aconduit occupying only a portion of the luminal cross-section of avessel, a whisk, a floating whisk, and the like.

Another aspect of the invention comprises a fistula device having aconduit and two flow frames, such as two whisks, wherein a whisk isprojecting from each end of the conduit and is configured to besurgically or percutaneously implanted, and further, may bepercutaneously maintained.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention, andtogether with the description serve to explain the principles of theinvention.

FIG. 1(a) illustrates a perspective view of an exemplary fistula devicecomprising a sidewall port device;

FIG. 1(b) illustrates a perspective view of an exemplary fistula devicecomprising a flow frame;

FIG. 2(a) illustrates a longitudinal view an exemplary fistula deviceshown deployed and coupled to an artery and vein, which are showncut-away to show portions of the device;

FIG. 2(b) illustrates a side view of an exemplary sidewall port deviceconnected to an exemplary conduit in an uncompressed state;

FIG. 2(c) illustrates a side view of a double-flanged end of anexemplary sidewall port device, as viewed in a plane generallyorthogonal to the direction of blood flow through the artery;

FIG. 2(d) illustrates a perspective view of a double-flanged end of anexemplary sidewall port device;

FIGS. 3(a) to 3(e) illustrate perspective views of various exemplaryconduits;

FIGS. 4(a) to 4(d) illustrate perspective views of various exemplarycompliant supports;

FIG. 5(a) illustrates perspective views of exemplary flow framescomprising conduits;

FIG. 5(b) illustrates a perspective view of an exemplary flow framecomprising a siphon conduit;

FIG. 6(a) illustrates a side view of an exemplary fistula devicecomprising two exemplary whisks;

FIG. 6(b) illustrates exemplary floating whisks and a side view of anexemplary floating whisk positioned in a vessel; and

FIGS. 7(a) to 7(c) illustrate an exemplary method of percutaneousdelivery of a fistula device.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Persons skilled in the art will readily appreciate that various aspectsof the present invention may be realized by any number of methods andapparatuses configured to perform the intended functions. Stateddifferently, other methods and apparatuses may be incorporated herein toperform the intended functions. It should also be noted that theaccompanying drawing figures referred to herein are not all drawn toscale, but may be exaggerated to illustrate various aspects of thepresent invention, and in that regard, the drawing figures should not beconstrued as limiting.

Although the present invention may be described in connection withvarious principles and beliefs, the present invention should not bebound by theory. For example, the present invention is described hereinin connection with anastomosis, such as vascular access fistula devices,in the context of hemodialysis in particular. However, the presentinvention may be applied toward any conduit connecting devices ormethods of similar structure and/or function, e.g. in aortic side-branchapplications. Furthermore, the present invention may be applied innonvascular applications and even non-biologic and/or non-medicalapplications.

Exemplary embodiments of the present invention are directed towarddevices and methods for use in anastomosis, and more specifically towarddevices and methods for creating new or reinforcing existing side-branchvessels, and/or bridging neighboring vessels together. One aspect of thepresent invention is directed toward sidewall ports and/or flow framedesigns for purposes of creating transmural flow through an aperture inthe sidewall of a vessel or stent device. Another aspect of the presentinvention is directed toward compliant vessel supports to aid in thetransition from device to vessel and/or vessel to device, and to promotevessel dilation. In combination, the present invention is directedtoward fistula designs modified with sidewall ports, flow frame designs,and/or compliant vessel supports that can be variously selected,interchanged and connected in any combination and configuration tofacilitate an anastomotic outcome.

In particular, exemplary embodiments of the present invention aredirected toward arteriovenous fistula (AV fistula) designs. Exemplary AVfistula designs may improve fistula circuit maturity rates such that thefistula may be immediately cannulateable and self-sealing and thereby,eliminate the need for a temporary catheter. Exemplary AV fistuladesigns may reduce the occurrence of stenosis or restenosis whilepromoting normal vein dilation. Similarly, exemplary AV fistula designsare sutureless and minimize pressure on vessel walls, thereby making theplacement and presence of the device less traumatic to a vessel.

Another exemplary embodiment of the present invention is directed towardaortic side-branch devices configured to engage an aortic stent-graftwall.

A fistula device, in accordance with the present invention, is a deviceconfigured to connect a first vessel to a second vessel to facilitateflow, e.g., transmural flow. As used in the context of aorticside-branches, a first vessel may comprise an aorta and a second vesselmay comprise an aortic side branch. As used in the context of AVfistulas, a first vessel may comprise an artery, and a second vessel maycomprise a vein. An AV fistula may direct blood flow from the artery tothe vein through a conduit so that the blood pressure at the venous endof the fistula may be sufficient for hemodialysis.

The above examples serve as illustrations of exemplary configurationsand these exemplary configurations are used throughout to explain thepresent invention. However, the present invention contemplates anyvessel-to-vessel configuration, vasculature or otherwise, including butnot limited to artery-to-vein, vein-to-artery, main branch-to-sidebranch, and side branch-to-main branch. As such, arterial and venousreferences are used as a means of explanation and should not be used tolimit the scope of the present invention.

A fistula device, in accordance with the present invention, may beimplanted surgically or percutaneously, e.g., endovascularly orotherwise. In addition, a fistula device, in accordance with the presentinvention, may be endovascularly maintained. For a percutaneouslyimplantable embodiment, a fistula device may comprise a compressedconfiguration and an expanded configuration. Moreover, the fistuladevice may be self-expandable.

A fistula device, in accordance with the present invention, may compriseany number of the elements selected from the following—sidewall ports,flow frame designs, compliant vessel supports, and conduits—which can bevariously selected, interchanged and connected in any combination andconfiguration to facilitate an anastomotic outcome. Furthermore, each ofthe elements may be configured to radially expand and contract with itshost vessel(s) in an effort to more closely match the compliance of thevessel(s).

Now with reference to FIG. 1(a), in accordance with an exemplaryembodiment, a fistula device 100 may comprise a sidewall port device 120coupled to the end portion of and co-luminal with a conduit 110 tocreate a branched system. Conduit 110 comprises a tubular componentconfigured to transport a fluid. Conduit 110 may be configured to createa new conduit, e.g. a bridging conduit, connecting two vessels and/orprovide support to a preexisting vessel proximate a junction. A distalportion 111 of conduit 110 may be modified to aid in the transition fromdevice 100 to a vessel, a vessel to device 100 or may be modified tohave a compliant support 113 attached thereto to promote vesseldilation.

A sidewall port device 120 is a device configured to join two conduitsat an angle to create or reinforce a junction of a branched vesselsystem and/or a bridged vessel system. (Both conduit modifications,bridged and branched systems, are referred to herein as a branchedsystem.) As such, sidewall port device 120 creates a substantiallyannular seal with the sidewall of a vessel so that a fluid, such asblood flowing through a vessel, does not leak from the branched system.For example, sidewall port device 120 may comprise a single-flanged ordouble-flanged device configured to extend radially with respect to anaperture in a vessel wall.

In lieu of or in addition to sidewall port 120, with reference to FIG.1(b), a fistula device 100 may comprise conduit 110 having a proximalportion 112 configured to allow to allow downstream perfusion inaddition to transmural flow. For example, conduit 110 may be modified toextend through a first vessel and an aperture in the vessel wall andhave a flow frame locatable in the lumen of the first vessel.

In an exemplary embodiment, with reference to FIG. 2(a), a fistuladevice 200 comprises an arterial segment 201, body segment 202, and avenous segment 203 having opposite proximal 212 and distal 211 portions.Fistula device 200 includes a generally continuous conduit 210 (the pathof which is illustrated by the dotted axis line) that extends betweenthe proximal 212 and distal 211 portions to allow blood flow (asindicated by the arrows) between an artery A and a vein V after adeployment of fistula device 200 in a body of a patient. Upondeployment, arterial segment 201 extends through a fenestration in theartery A. The fenestration may be created surgically or percutaneously,e.g., endovascularly or otherwise. Upon deployment, venous segment 203extends through a fenestration formed in the vein V. Body 202 extendslongitudinally between arterial segment 201 and venous segment 203.Conduit 210 extends through each of the arterial 201, venous 203 andbody 202 segments of fistula device 200.

An alternative to fistula device 200 extending through an aperture maycomprise one end of a cut vessel repositioned over fistula device 200,such that the cut vessel and fistula device 200 connect, e.g., end toend or overlapping. In this embodiment, the other end would be ligatedor otherwise closed off.

Conduit 210 comprises a tubular component configured to transport afluid. Conduit 210 may comprise a prosthetic or biological material. Atubular component comprises a biocompatible material, whether polymericor metallic, which can be varied or used in combination to obtaindesired support or flexibility properties. A tubular component may berigid or very flexible and bendable. Similarly, a rigid conduit 210 maycomprise a straight or angled configuration as is required by thedesired configuration. Conduit 210 when bent, twisted or torqued may bestructurally and/or materially configured to do so without kinking.Conduit 210 may also be configured to be length adjustable.

Conduit 210 may also be configured such that the diameter can becustomizeable and/or variable such as that disclosed in U.S. Pat. No.6,336,937 to Vonesh et al., which is incorporated herein by reference.For example, conduit 210 may be deployed at a first diameter, expandedto a second diameter, and enlarged by application of a distensive force,such as through use of a balloon dilatation catheter or via controlledcreep processes engineered into conduit 210, to variable thirddiametrical dimensions to fit the dimensions of the vessel or adjust tochanging dimension of the vessel.

For example, with reference to FIG. 3(a), conduit 310 may utilize abendable or flexible tube design having reduced-diameter sections orindentations 314 that define individual segments 315. Indentations 314allow the tube to be bent or contorted along a tight curve by elongatingon the “outside” of the curve and compressing on the “inside” of thecurve. The segments 315 also have an increased radial strength to allowthe lumen defined by the tube to remain open when severelybent/distorted during placement and deployment in tortuous anatomy.Adjustability may be achieved by the selective semi-densification ofindentation 314 of the tube. Under tension (provided by the implantingclinician) semi-densified indentation 314 will lengthen, therebyallowing the clinical benefit of tailoring the length of fistula deviceat time of implant.

In another embodiment, with reference to FIG. 3(b), conduit 310 maycomprise graft walls 318, such as those made from a thin polymericmaterial like ePTFE, and/or a stent 319. Stent 319 may comprise anyconfiguration to achieve the preferred amount of bendability andsupport. For example, stent 319 may comprise a series of wire ringstents or a helical, multi-turn stent which are attached to the graftwalls 318 by a film (not shown). The ring or helical turned frame ofstent 319 may further comprise undulations (as depicted in FIG. 3(b))wherein the film only partially covers the wire undulations. Thisconfiguration allows conduit 310 to bend within 360 degrees withoutkinking and improves the conformability of the device to the vessel walland the ability to traverse through aperture 325.

Another conduit 310, with reference to FIG. 3(c), may comprise a thin,“wispy” tube design such as that disclosed in U.S. Pat. No. 5,800,522,which is incorporated herein by reference. In this embodiment, conduit310 may circumferentially distend from its initial circumference uponthe application of a circumferentially distending force such as appliedby an internal pressure, and which exhibits minimal recoil following theremoval of the circumferentially distending force. As such, conduit 310may comprise a second circumference larger than the initialcircumference that remains substantially unchanged by further increasingforce once it is achieved. A clinician simply trimming the tail of thetube to a desired length may achieve adjustability.

Alternatively, with reference to FIGS. 3(d) and 3(e), conduit 310 maycomprise a tubular member that (i) terminates at a junction with aneighboring element and/or (ii) connects end to end with a vessel. Inthis embodiment, a tubular member may be more rigid and less bendablethan the conduit embodiments previously described because conduit 310 isnot required to conform to and/or extend through vessels A or V. Conduit310 may be straight or bent at a preferred angle or curvature suitablefor the desired configuration. In an exemplary embodiment, conduit 310comprises a polymeric material such as ePTFE, and optionally, maycomprise, biodegradable material, such as a polyglycolide-co-primethylene carbonate (PGA:TMC) or other similar.

With reference to FIGS. 3(d) and 3(e), conduit 310 may optionallycomprise a suture retention ring 360 at a proximal and/or distal end.Suture retention ring 360 may comprise a densified area or an areaotherwise reinforced so that an end of a vessel or an aperture in avessel wall may fit about conduit 310 and be connected thereto in anysuitable manner, e.g., by clamping, tying, or suturing the vessel toconduit 310.

Referring back to FIG. 2(a), conduit 210 may comprise a compliantsupport 213. Compliant support 213 is configured to radially expand andcontract with its host vessel in an effort to more closely match thecompliance of the vessel. For example, compliant support 213 may beformed within venous segment 203 and expand outwardly (e.g., in a flaredconfiguration) from distal portion 211 of fistula device 200 towardinner walls of the vein V. Compliant support 213 may also be formedwithin arterial segment 201 or any other area where compliancy isdesired or beneficial. Compliant support 213 comprises any flexiblestructure that once deployed is generally compliant to minimize radialdistension of a vessel. In the instance of a percutaneously deployablefistula device 200, compliant support 213 may comprise a compressedconfiguration and an expanded configuration, and may further have aself-expanding (elastic) or plastic configuration.

Compliant support 213 may have a generally tapered, bell orfrusto-conical shape in an uncompressed state. (Exemplary embodiments ofcompliant support 413 are illustrated in FIGS. 4(a) to 4(d).) Forexample, compliant support 213 comprises a tapered, bell orfrusto-conical frame. The frame of compliant support 213 comprises anybiocompatible material, such as Nitinol, that can make a compliant andflexible frame. The frame of compliant support 213 may be formed ofmetallic or polymeric filament or cut from tubing or both. A filament inturn, may be formed into a closed ended braided design, a criss-cross orover-lapping design, an undulating series of rings or helix, or anyother design, which creates a compliant support 213.

Compliant support 213 may be integral with or fixedly secured to fistuladevice 200 by any suitable mechanism. For example, annular band 217 maysecure compliant support 213 to fistula device 200. Annular band 217 maybe formed from a flexible film, such as ePTFE. In one embodiment,compliant support 213 is spaced apart from distal portion 212 andcoupled thereto solely by the annular band 217. Alternatively or inaddition, compliant support 213 may be fixedly secured, for example bywelding or suturing to fistula device 200 that forms a part of thevenous segment 203.

While not required, compliant support 213 may comprise a flexible filmlining, such as ePTFE. In an exemplary embodiment, the flexible filmlining may be configured to reduce or block retrograde blood flow.Further, a film lining may enhance or improve cellular in-growth orbiocompatibility.

Compliant support 213 may be any configuration that exerts slight, butconstant pressure on the vein V. This constant pressure will causevascular remodeling to occur over time, resulting in eventual dilationof the vein. This dilation may have an upper limit set by compliantsupport 213. Once remodeling has ceased, compliant support 213 willallow diametrical fluctuation as determined by blood pressure. It isknown that changes between systole and diastole, use of medication, andphysical exertion all affect blood pressure. Compliant support 213 isconfigured to radially expand and contract with its host vessel in aneffort to more closely match the compliance of the vessel and therebyreduce late outflow stenosis. It should be appreciated that this featureof fistula device 200 could be applied to other regions of mammaliananatomy also with enhanced benefit. Other venous applications arepossible, as well as increased efficacy of arterial, esophageal andintestinal devices can be realized.

In an exemplary embodiment, fistula device 200 comprises sidewall portdevice 220 in the arterial segment 201 coupled to or integral withconduit 210. For example, sidewall port device 220 may comprise a firstflange 221, which extends generally radially and generally defines anaperture 225. Upon deployment of fistula device 200, first flange 221engages an arterial wall to secure fistula device 200 to the artery A.The outer peripheral dimension of flange 221 may range from being onlyslightly up to substantially larger than aperture 225. In an exemplaryembodiment, with reference to FIG. 2(b), first flange 221 may beconfigured so arterial pressure may press flange 221 against thearterial wall in order to engage the wall. In addition, first flange 221may also comprise at least one anchor 226, e.g. a hook or the like, toengage the arterial wall. It should be noted that while not required,sidewall port device 220 may further optionally comprise a second flange222, as also shown in FIG. 2(a).

By way of further example, and with reference to FIG. 2(c) and FIG.2(d), sidewall port device 220 may comprise a first flange 221 andsecond flange 222, both which extend generally radially and generallydefine an aperture 225. The second flange 222 is axially spaced apartfrom the first flange 221 to receive a portion of a vessel wallthere-between upon deployment, such that the first 221 and second 222flanges are configured to mechanically engage opposite luminal andabluminal surfaces “a1” and “a2” of the vessel wall to secure thesidewall port device 220 and/or a fistula device to the vessel wall.

Flange 221, 222, whether a single or dual configuration, may comprise alattice 223 (FIG. 2(a)) that is self-expanding or self-setting. Forexample, lattice 223 may radially and outwardly bias the flanges 221,222 toward an outer peripheral dimension that is larger than that ofaperture 225. When a tension force is applied, flanges 221, 222 elongateto a reduced profile, but when the tension force is removed, built-inbias of lattice 223 facilities flanges regaining their neutral, outerperipheral dimension. For example, lattice 223 may comprise a generallydiamond-shaped, petal-like pattern, or any other flexible configurationthat can be elongated to reduce its profile and retract back to itsneutral, flanged configuration upon relaxation of a tension force. Suchreduced profile facilitates a percutaneous placement.

Lattice 223 may be formed from either a single filament or a pluralityof filaments. The filaments may comprise a Nitinol, Elgiloy or othersuitable biocompatible metals or polymers. The cross-section of thefilaments may be round, square, rectangular, oval, polygonal, or othergeometric shape. Lattice 223 may be covered or lined in with a flexiblepolymeric film, such as an expanded polytetrafluorethylene (ePTFE) film.In FIGS. 2(a) through 2(d), both multiple and single filament latticestructures are depicted, but the desired sutureless anastomosis may beachieved with a formed laser-cut tube as well.

Although a self-expanding lattice is preferred (due to implant siteproximity to the skin surface and risk of accidental or inadvertentexternal compression), flange 221, 222 may comprise any collared orrimmed structure that can be fixedly secured to a vessel wall aboutaperture 225—whether comprised of filament(s), molded feature(s), orotherwise—such as a plastically deformable flange structure asillustrated in FIG. 3(d).

In an exemplary embodiment, with reference to FIG. 2(c), sidewall portdevice 220 may comprise first flange 221 and/or second flange 222 formedfrom a tube 224 comprising lattice 223 inverted onto itself to form aninner tube disposed coaxially within an outer tube. Flanges 221, 222 maybe formed along the outer tube. The inner and outer tubes transition atan outer peripheral edge of the first flange. In an exemplaryembodiment, tube may further extend from sidewall port device 220 tofunction as a stent graft, or alternatively a stent graft may be coupledto the sidewall port device 220. However, sidewall port device 220 neednot be configured from a tube. Sidewall port 220 comprises any structurehaving a first flange 221, which extends generally radially andgenerally defines an aperture 225 and is configured to engage anarterial wall.

It should be readily appreciated that the sidewall port device, e.g.,the anchored single flange and dual flanges, and the flow framedescribed below can be utilized for anchoring and sealing otherendoluminal devices, such as stent grafts, in other areas of thevascular system and other bodily conduits, such as aortic side branches,coronary bypass grafts, artificial gastrointestinal stomas and the like.A stent graft according to an alternative embodiment includes dualflanges for coupling the stent graft through a clinically made aperturein a vascular wall or wall of another prosthesis. Each flange of thedual flanges extends radially outwardly with respect to the aperture.Each flange mechanically engages generally opposite sides of the wallsurrounding an aperture for fixedly securing the stent graft to thewall. In another embodiment, a stent graft includes a single flange forcoupling the stent graft through an aperture in a wall. The singleflange extends generally radially outwardly from an end of the graft andresides in proximity to the luminal wall of the artery upon deployment.The single flange mechanically engages the luminal wall and is held inplace against the wall by vessel pressure and/or interference fit. Thesingle flange portion reduces the effect of necrosis of the vessel byreducing the pinch force of the vessel wall.

Now with reference to FIGS. 5(a) to 5(b), in an exemplary embodiment,fistula 500 comprises a flexible conduit 510, as described above, and aflow frame 530 in arterial segment 501. Fistula 500 may further comprisea compliant support 513, as described above, in venous segment 503.

Flow frame 530 is configured to span at least a portion of the lumen ofa vessel proximate the aperture when deployed. Flow frame 530 is usuallyconfigured to allow to allow downstream perfusion in addition totransmural flow. Similarly, the present invention contemplates flowframe 530 alternatively configured to block or reduce retrograde bloodflow. A portion of flow frame 530 may extend through an aperture in avasculature wall or prosthetic device.

Flow frame 530 may comprise a compressed configuration and an expandedconfiguration. Moreover, flow frame 530 may be self-expanding.

For example, flow frame 530 may comprise a portion of conduit 510comprising stent 519 as described above with a portion of graft material518 in the area of an elbow or bend in the conduit cut-away, i.e. barestent 519, to allow downstream perfusion in addition to transmural flow.Graft material 518 may terminate in any fashion to reveal bare stent519; e.g., graft 518 may terminate at a straight or angled cut to revealbare stent 519 or be a cutout of any shape and size proximate aperture525, e.g., the cutout may be formed with straight and/or angled cuts toform an angled cutout or any other cutout. Other exemplary embodimentsof flow frame 530 may comprise a bifurcated branch or a conduit windowor opening of any shape locatable at an elbow or bend in conduit 510,for example, a conduit window or opening formed with curved, straight,or angled cuts to form a cutout of any shape or size, including anangled cutout.

Alternatively, with reference to FIG. 5(b), flow frame 530 may comprisea siphon conduit 570 that occupies only a portion of the luminalcross-section of a vessel to allow downstream perfusion in addition totransmural flow. Siphon conduit 570 comprises an inlet 571 sized so asto allow sufficient flow into the diverted segment yet still allow forsufficient downstream perfusion (e.g., in the context of AV fistulas, tominimize the chance of Steal Syndrome).

Alternatively, with reference to FIG. 6(a), flow frame 630 may comprisewhisk 631. Whisk 631 comprises any framework 632 configured to span atleast a portion of a lumen proximate an aperture when deployed to allowto allow downstream perfusion in addition to transmural flow. Forexample, framework 632 may comprise any open structure which whendeployed does not block or significantly obstruct flow through thenative conduit, e.g. rib(s) or a crisscross structure. Whisk 631 mayhave a generally curved profile at points of contact to minimize anyvessel wall trauma thereabout. Whisk 631 may be composed of anybiocompatible material, whether polymeric, metallic or combinationsthereof, e.g., ePTFE and/or Nitinol, and may be formed of ribs orinterwoven/interconnected bands or cut from tubing or both.

Whisk 631 may comprise a compressed configuration and an expandedconfiguration. Moreover, whisk 631 may be self-expanding.

Whisk 631 may be configured to allow or re-direct normal blood flow, orreduce or block retrograde blood flow. For example, framework 632 may bepartially covered with film 634 and at least partially spanning a lumencross-section to reduce or block flow. Similarly, whisk 631 may beconfigured to minimize fluid turbulence, or alternatively to increasefluid turbulence. For example, ribs may comprise a bladed profile thatwhen deployed are positioned in a manner to reduce turbulence.

Whisk 631 may be configured to seal a vessel wall puncture site. Forexample, whisk 631 may comprise a cap 633 on distal end that whendeployed presses against vessel wall opposite aperture 625. A punctureon vessel wall generally opposite aperture 625 would then be sealed bycap. Cap 633 may be further imbibed with a therapeutic agent, such as alocalized clotting agent or antibiotic, to further promote sealingand/or improve rate of healing.

Whisk 631 may be integral with or fixedly secured to conduit 610, asdescribed above, by any suitable mechanism. For example, an annularband, as described above, may secure whisk 631 to conduit 610. Annularband is formed from a flexible film or tape, such as ePTFE.Alternatively or in addition, whisk 631 may be fixedly secured, forexample by welding or suturing to conduit 610.

Whisk 631 may exert slight, but constant pressure on a vessel. Thisconstant pressure will cause vascular remodeling to occur over time,resulting in eventual dilation of the vessel. This dilation will have anupper limit set by whisk 631. Once remodeling has ceased, whisk 631 mayallow diametrical fluctuation as determined by blood pressure. It isknown that changes between systole and diastole, use of medication andphysical exertion all effect blood pressure. Whisk 631 may be configuredto radially expand and contract with its host vessel in an effort tomore closely match the compliance of the host vessel and thereby reducelate outflow stenosis.

In an exemplary embodiment, fistula device 600 may comprise conduit 610,a first whisk 631 and a second whisk 635, wherein first whisk 631 isprojecting from one end of conduit 610 and the second whisk 635 isprojecting from the other end. At least one whisk 631, 635 may comprisecap 633 to seal a puncture site created to percutaneously deploy fistuladevice 600. Fistula device 600 may be self-expandable.

With reference to FIG. 6(b), whisk 631, as described above, may also beconfigured to function as a “floating” whisk 631 to span a portion of,or the entire cross-section of a lumen or aperture. Floating whisk 631can be positioned anywhere within the lumen of a vessel, fistula device,or prosthetic device, through an aperture or otherwise, for purposes ofproviding structural support, i.e., holding an aperture or vascularwalls open to prevent collapse. Floating whisk 631 may be surgically orendovascularly removable if desired.

The present invention also contemplates methods for implantingsurgically or percutaneously a fistula device as described herein, aswell as method of performing maintenance endovascularly on a previouslyimplanted fistula device. In exemplary embodiments, the presentinvention provides for a mature fistula which may be characterized as(i) having at least a 4 mm, more preferably at least a 6 mm diameter,(ii) being less than 8 mm, more preferably less than 6 mm from the skinsurface, and/or (iii) facilitating 400 mL/min of blood flow, morepreferably 600 mL/min of blood flow.

For example, an exemplary method of delivery may comprise the steps ofpassing a first catheter through a first vessel wherein the firstcatheter comprises a side port and ramp to radially direct a flexiblepiercing device, second catheter; or other elongate member though thesideport. An exemplary piercing device may comprise a continuous lumenthere through.

The next step in an exemplary method of delivery may comprise passingthe piercing device through the lumen of the first catheter; piercingthe sidewall of the first vessel and piercing the sidewall a secondvessel with the piercing device; and entering lumen sufficiently to sothat a guidewire may enter the lumen of a second vessel as it exits thedistal tip of the piercing device. In an exemplary embodiment, the nextstep may comprise passing a fistula device as described herein, whichmay be loaded onto a catheter over the guidewire into a desired positionfor deployment. For example, with regard to an AV fistula, the desiredportion may comprise a proximal portion within an arterial segment and adistal portion within a venous segment.

In an exemplary embodiment, with reference to FIGS. 7(a) to 7(c), amethod of delivery comprises the steps of passing a hollow needle 740through a first vessel 750 wherein within the lumen of hollow needle740, a compressed fistula device 700 comprising conduit 710, first whisk731 and second whisk 735 as described above resides; entering the lumenof a second vessel 751 with hollow needle 740; deploying first whisk 731in lumen of second vessel 751; retracting the hollow needle 740 fromfistula device 700; and thereby deploying second whisk 735 in firstvessel 750. First vessel 750 and second vessel 751 may comprise anartery or a vein.

In an exemplary embodiment, a method of maintenance comprises the stepsof endovascularly deploying a balloon or other endovascular tool to thesite where a fistula device (as described herein) has been previouslyimplanted for purposes of inspection, repair, or maintenance

All components described herein may be imbibed or coated with atherapeutic agent; e.g., heparin or any other antithrombotic agents.

As stated previously, it should be readily appreciated that theembodiments described herein are not an exhaustive recount of allpossible embodiments. The components described herein, namely sidewallports, conduits, flow frames (e.g., modified conduits or whisks), andcompliant supports, can be variously selected, interchanged andconnected in any combination and configuration to facilitate ananastomotic outcome.

It should be noted that various implantation schemes are envisioned.This device may be surgically implanted or endoluminally deployed inplace. Both surgical and endoluminal versions may contain radiopaquemarkers to assist in 1) initial implantation and 2) subsequentinterrogation “maintenance” procedures. The device may come pre-packagedand radially constrained within a delivery system to facilitate accurateand quick placement. This delivery system may be configured long enoughfor remote access to a vessel, such as from the brachial artery, or veryshort to be used by a vascular surgeon. The delivery devices and systemswill also be configured with imaging enhancements to assist in locatingand guiding these devices during use. Enhancements may include echogenicand or radiopaque markers.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A fistula device comprising: an expandableunbranched frame defining a conduit having a first end configured to bepositioned in a first vessel and a second end configured to bepositioned in a second vessel; and a cover coupled to the expandableunbranched frame, the cover defining an inner lumen configured to conveyfluid and including an opening positioned between the first end and thesecond end to allow downstream perfusion in the first vessel through thefirst end and the opening, wherein the opening is configured to belocated at or near a bend in the expandable unbranched frame such thatthe opening is located opposite the first end within the first vessel.2. The fistula device of claim 1, wherein the first vessel is an arteryand the second vessel is a vein.
 3. The fistula device of claim 2,wherein the opening of the cover is defined by a straight or angled cutterminating through the cover.
 4. The fistula device of claim 1, whereinthe fistula device is configured to be percutaneously deployed.
 5. Thefistula device of claim 1, wherein the expandable frame includes acompliant support positioned near the second end of the expandable frameconfigured to expand outwardly toward the inner walls of the secondvessel.
 6. The fistula device of claim 5, wherein the compliant supportis comprised of Nitinol.
 7. The fistula device of claim 5, wherein thecompliant support is sufficiently flexible and compliant to minimizeradial distention of the vessel after deployment.
 8. The fistula deviceof claim 1, wherein the opening is positioned at a first cover perimeterposition defined by the cover and the cover is directly supported by theexpandable unbranched frame at a second cover perimeter position, thefirst cover perimeter position being directly opposite the inner lumenfrom the second cover perimeter position.
 9. A method of re-directingfluid flow with the fistula device of claim 1, comprising: deploying thefirst end of the expandable unbranched frame of the fistula device in afirst vessel having a first wall; bending the expandable unbranchedframe within the first vessel; positioning a first portion of thefistula device downstream of the bend in a first fenestration of thefirst wall; positioning a second portion of the fistula device in asecond fenestration of a second wall of the second vessel; and deployingthe second end of the fistula device in the second vessel.
 10. Themethod of claim 9, wherein the fistula device is deployedpercutaneously.
 11. The method of claim 9, wherein the first vessel isan artery and the second vessel is a vein.
 12. A fistula devicecomprising: an expandable frame defining a tubular shape having an innerlumen and defining a first end portion configured to be implanted in afirst vessel and a second end portion configured to be implanted in asecond vessel; and a cover coupled to the expandable frame, the coverhaving an opening in the wall of the cover that opens directly into theinner lumen, the frame configured to include a bend between the firstand second end portions at the opening, the cover having an angledcutout forming the opening such that the opening is operable to allowdownstream perfusion in the first vessel through the first end portionand the opening in the wall.
 13. The fistula device of claim 12, whereinthe first vessel is an artery and the second vessel is a vein.
 14. Afistula device comprising: an expandable frame defining a conduit havinga first end configured to be positioned in a first vessel and a secondend configured to be positioned in a second vessel, the expandable frameincluding a bend between the first end and the second end; and a covercoupled to the expandable frame, the cover defining a continuous innerlumen between the first end and the second end, the continuous innerlumen configured to convey fluid and including an opening positionedbetween the first end and the second end at or near the bend to allowfor downstream perfusion and transmural flow such that the opening islocated opposite the first end within the first vessel.
 15. The fistuladevice of claim 14, wherein the first vessel is an artery and the secondvessel is a vein.
 16. A fistula device comprising: an expandableunbranched frame defining a conduit having a first end configured to bepositioned in a first vessel and a second end configured to bepositioned in a second vessel; and a cover coupled to the unbranchedexpandable frame, the cover defining an inner lumen configured to conveyfluid and including an opening having edges forming straight lines andpositioned between the first end and the second end at a firstlongitudinal position to allow downstream perfusion in the first vesselthrough the first end and the opening, wherein the cover is directlysupported by the expandable unbranched frame at a second longitudinalposition directly opposite the inner lumen from the first longitudinalposition.
 17. The fistula device of claim 16, wherein the openingdefines an angled cutout.